1. Field of the Invention:
This invention relates to an improvement of a transfer type electrostatic reproducing apparatus provided with a pretransfer exposure lamp to expose the surface of a photosensitive member before transfer after toner development.
2. Description of the Prior Art:
A pretransfer exposure improves a print efficiency of a toner image onto a transfer paper to lower the surface potential of a photosensitive member after toner development and also exerts an influence on a detachability at the time of detaching the transfer paper from the photosensitive member by means of a separating electrode. A conventional type of electrostatic reproducing apparatus provided with such a pretransfer exposure lamp operates on a system wherein the pretransfer exposure lamp irradiates the photosensitive member surface with a constant quantity of light at all times irrespective of the thickness and size of a transfer paper, and the transfer paper is detached by the separatng electrode at a constant discharge current. An irradiation on the photosensitive member surface by means of the pretransfer exposure lamp as described may invite a problem that the photosensitive member will be fatigued to shorten a lifetime as indicated in FIG. 1. FIG. 1 indicated a potential change on the photosensitive member surface before development after projection of an original image in a repetitive transfer, which is given from carrying out a pretransfer exposure with a light a 30 lux sec. by means of a cold cathode fluorescent tube having a peak at about 400 nm for a pretransfer exposure lamp and also from not carrying out the pretransfer exposure, with the transfer conditions other than the pretransfer exposure kept constant and same.